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Seedless Plants/Transcript
Transcript Text reads: The Mysteries of Life with Tim & Moby Moby is playing the video game "Earth Builder 2.0". Tim is wearing a shirt with a picture of a plant on it. TIM: Ha! Good luck trying to start an ecosystem there. MOBY: Beep! TIM: Well, if I were playing, I'd... I'd start by sprinkling in some mosses. Maybe a few liverworts, too. An animation shows a computer screen. On the computer screen, a very harsh environment of rocks and volcanoes is shown. A cursor is moving from the text "Moss" and "Liverwort" to various spots on the screen. The cursor leaves moss and liverwort throughout the screen. A message pops up onto the computer screen. Tim reads the message. TIM: Dear Tim and Moby, can you tell me about mosses and ferns? From Angie. MOBY: Beep? TIM: Yup, they are indeed plants. Like all other plants, mosses and ferns are eukaryotic, meaning their cells have a nucleus. They also contain cell walls made of cellulose, a tough, fibrous material. And they're autotrophic, which means they make their own food. An image shows a plant cell. On the cell, a number of its structures are shown. An oval shape with a sphere at its center is labeled "nucleus". The outside surface of the cell is labeled "cell wall". Throughout the cell, a number of dark green spheres are shown, labeled "chloroplast". TIM: In particular, they carry out photosynthesis, a process that turns carbon dioxide into sugar! Unlike most plants, though, mosses and ferns don't reproduce with seeds. Those are basically tiny, undeveloped plants in a protective coating. An animation shows a seedling that grows into a plant. MOBY: Beep? TIM: Instead of seeds, mosses, ferns, and other seedless plants use special reproductive cells called spores. An image shows a figure that resembles a bush. Sprouting from the figure are three stem-like objects. Connected to the tip of each is an oval. A large circle is connected to one of the ovals. Inside the circle, a group of sphere clusters is shown. Text reads: Spores. TIM: Spores are so tiny that when a mature plant releases them into the air, the wind can easily disperse them over great distances. And if a spore lands somewhere with the right conditions, it can grow into a whole new plant! An animation shows the sprouting stem-like objects swaying in the wind. One of the ovals at its tip rips open and releases a cloud of tiny spheres. The cloud travels until it lands on a cliff and grows into a small figure that resembles a bush. MOBY: Beep? TIM: Well, just because they all grow from spores doesn't mean seedless plants are all the same. They're actually broken into two main types: vascular and nonvascular. An image shows a plant with a stem and a number of narrow leaves, labeled "vascular", and a plant that resembles a flat bush, labeled "nonvascular". TIM: Vascular seedless plants have channels that carry water and nutrients throughout their bodies—sort of like veins and arteries! An animation shows a vascular plant sprouting from the ground. Its roots are shown absorbing liquid. Another image shows a cross section of a vascular plant stem. TIM: Ferns are the most common of these—there are more than 12,000 different species! The screen is divided into three equal sections. The sections contain a group of plants growing in a jungle, a group of plants growing in snow, and a group of plants growing in a desert. TIM: Like all vascular plants, ferns have specialized channels for water transport, as well as roots and stems similar to those in seed plants. That allows them to grow pretty tall—sometimes more than 15 feet! An image shows Moby standing next to a fern that is much taller than Moby. TIM: Ferns also have spiral-shaped structures that uncurl into broad leaves called fronds, many of which produce spores. The screen is divided into two equal sections. In one section, a spiraled stem of a plant is shown. In the other section, there is a plant with a long stem and many narrow leaves. TIM: Other vascular seedless plants include ground pines and spike mosses with their needle-like leaves; and horsetails with their jointed stems. They all produce spores at the tips of their stems, in structures that look like miniature pine cones. Three images are shown: a plant with a number of overhanging branches labeled "ground pine", a plant with stems full of pointy leaves labeled "spike mosses", and a plant with a stem that is separated into leafy sections labeled "horsetails". MOBY: Beep? TIM: Nonvascular seedless plants, or bryophytes, have simpler structures! An image shows a plant that resembles a flat bush. There are a number of stems sprouting from its surface: a plant that resembles a head of lettuce, a plant with a body that looks like flattened leaves, and a plant that resembles a section of plush carpet. TIM: Instead of vascular channels, they transport water and nutrients directly through their thin cell walls. An animation shows rain falling on the plant that resembles plush carpet. A large circle is connected to the plant. Inside the circle, a magnified version of the rain is shown. Three connected spheres labeled Upper H, Upper H, Upper O are passing through the circle. TIM: It helps that most bryophytes are just a few cells thick and don't grow taller than a few centimeters! Thin root-like threads called rhizoids hold the plant in place and also absorb water from the ground. An image shows the roots of a plant. TIM: You'll find bryophytes all over the world in damp environments with plenty of moisture, like forest floors or near ponds, lakes, and streams. The screen is divided into two equal sections. In one section, a group of differing plants is shown in a forest environment. In the other section, a group of differing plants is shown near a waterway and waterfall. MOBY: Beep? An animation shows Moby pointing to the moss on the computer screen. TIM: Yup. Mosses are the most common type of bryophyte! They grow in clumps or layers on the ground, tree trunks, or even rocks. An image shows green plants growing very close to the ground around the base of tree trunks. TIM: From a distance, they might look like fuzzy green carpets; but up close, they're actually made of leaf-like growths around short, wiry stalks. MOBY: Beep? An animation shows Moby point to a plant on the computer screen. TIM: That's one of the thousands of species of liverworts, funny-looking bryophytes with bodies that look like flattened leaves. An image shows a liverwort. MOBY: Beep? TIM: True, this lava field doesn’t look like the best home for any type of life. But mosses and liverworts are among the first plants to grow in harsh environments like these! An image shows mosses and liverworts growing throughout an environment full of cooled lava and rocky terrain. A volcano is smoking in the background. TIM: Spores carried by wind onto bare rocks can survive for a long time in dry conditions. An animation shows Tim moving and clicking the computer mouse. TIM: All they need is a little moisture to start growing! On the computer screen, a rain cloud with rain falling is moving over the mosses and liverworts that Tim planted in the game. TIM: When these first plants die, decaying plant matter starts to build up. This kick-starts the process of soil formation, gradually creating an environment where other plants can grow. The mosses and liverworts are shown decaying and disappearing, causing a large section of the ground to turn brown. A number of plants are shown sprouting from this brown section. MOBY: Beep? TIM: Yup, that's why seedless plants played such an important role in the evolution of life on Earth! Hundreds of millions of years ago, when all the dry land was rock, bryophytes were the only plants that could grow. They broke down the soil enough for ferns to grow as well. And that provided an environment for the animals that followed. An animation shows a group of differing plants. A dinosaur is shown running across the screen. TIM: Over time, the layers of dead plant matter from these original species formed much of the coal we use today for fuel! MOBY: Beep! An animation shows Moby point to the computer screen. In the computer game, an avatar of Moby is shown plowing the land with a farm tractor. TIM: Okay, now you're just cheating. Category:BrainPOP Transcripts Category:BrainPOP Science Transcripts